In recent years, secondary batteries have attracted considerable attention as a power source for electric vehicles (EV) and hybrid electric vehicles (HEV), which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles using fossil fuel.
Small-sized mobile devices use one or several battery cells for each device. On the other hand, middle or large-sized devices, such as vehicles, use a battery module having a plurality of battery cells electrically connected to each other because high output and large capacity are necessary for the middle or large-sized devices.
Preferably, the battery module is manufactured so as to have as small a size and weight as possible. For this reason, a prismatic battery or a pouch-shaped battery, which can be stacked with high integration and has a small weight to capacity ratio, is usually used as a battery cell of the battery module. In particular, much interest is currently focused on the pouch-shaped battery, which uses an aluminum laminate sheet as a sheathing member, because the pouch-shaped battery is lightweight, the manufacturing cost of the pouch-shaped battery is low, and it is easy to modify the shape of the pouch-shaped battery.
In order for the battery module to provide output and capacity required by a specific apparatus or device, it is necessary for the battery module to be configured to have a structure in which a plurality of battery cells is electrically connected in series to each other and the battery cells are stable against external force.
In a case in which a battery module is manufactured using a plurality of battery cells, therefore, a plurality of members for mechanical fastening and electrical connection between the battery cells is generally needed and, as a result, a process of assembling the mechanical fastening and electrical connection members is very complicated. Furthermore, there is needed a space for coupling, welding, or soldering the mechanical fastening and electrical connection members with the result that the total size of a system is increased. The increase in size of the system is not preferable in the terms of spatial limitations of an apparatus or device in which a middle or large-sized battery module is installed. Moreover, the middle or large-sized battery module must be configured to have a more compact structure such that the middle or large-sized battery module can be effectively installed in a limited inner space, such as a vehicle.
In particular, a plurality of parts is needed to stack a plurality of battery cells in a fixed state. For example, it is necessary to accurately and stably fix the battery cells in place using battery cell fixing parts. As a result, an assembly process is complicated and difficulty of a manufacturing process is increased. In addition, the volume and weight of the battery module are increased and the manufacturing cost of the battery module is raised.
Therefore, there is a high necessity for a battery module which can be manufactured to have a simple and compact structure and in which the number of parts constituting the battery module is reduced to improve efficiency of an assembly process while decreasing the manufacturing cost of the battery module.